Abstract: Three-dimensional models of heat transfer for a die with seven different geometrical dimensions of die holes and three different geometrical dimensions of channels of conduct oil of pelletizing under water were created and solved by numercial simulation to obtain temperature field inside the die. The temperature field of the die under the conditions of different temperatures of cooling water, different coefficients of heat transfer of heating oil, different materials were also calculated. Due to the cooling effect of water, the temperature of the surface of pelletizing zone of the die was relatively low in the direction along the thickness; due to the heating effect of heating oil and polymer, the temperature of the deep zone of pelletizing zone of the die was gradually increased. Combined effects of heating of oil and cooling of water led to greater gradient of temperature close to the pelletizing surface, in the range of 0 z  10mm. Through analysis, it was found that the geometrical dimensions of the die hole did not affect the temperature field of the die; while the form of channels of heating oil, the temperature of cooling water, heat transfer coefficient of heating oil, and the material of the die did. These results provided a reliable theoretical basis for the structural design of die, determination of the boundary conditions, and the choice of materials.

Key words: polymer, die for pelletizing under water, temperature field, numerical analysis